In order to make mashed potato, the potato is first cooked as evenly as possible. If the starch grains in the potato are ruptured, they release Amilose, imparting a ‘gluey’ texture. Amilose is the thickening medium in gravy and custard. These starch grains can be ruptured by either excessive heat or kinetic energy.
Best results are obtained by slicing the potato before boiling. Thick lumps overcook on the outside and release Amilose before the centre is softened. For perfect mash, the cooked potatoes should be washed before being mashed.
Once softened the potato is crushed to remove lumps then blended with milk, butter, herbs etc to taste. Mashed potato is eaten in most countries under various guises.
High speed choppers and food processors break down the starch grains and do not produce an acceptable result. They use high speed as a means of ‘catching’ the suspended lumps and breaking them up.
The problem with a traditional hand masher in a saucepan is that hard lumps keep moving out of the way of the crushing bars. Unless the potato or the like is perfectly cooked it can become very difficult to remove all lumps.
Commercial mashers, (or ricers as they are commonly called), use either a blade or a plunger to force material through a sieve. They have the limitation of being large and difficult to clean, and often difficult to use.
At least one powered masher for domestic use is known. This device, marketed under the brand name Kenwood®, comprises an attachment for a “stick mixer” and includes a cylindrical skirt open at the underside and a top with apertures. A blade rotates in the skirt and forces food particle up through the apertures. Problems with this arrangement are firstly, it takes considerable force to repeatedly push the device into the food stuff to be mashed as the blade appears to push the food down against the bottom of the container and, secondly, food stuff extruded through the apertures in the top of the skirt tend to adhere thereon so that repeated impacting or scraping is required.
A further problem of this masher is that to remove the blade for cleaning, the masher assembly must be attached to the power unit. The blade is attached to its drive shaft by means of a screwing “bayonet” fitting and it requires, the torque of the reduction gearing of the power unit to counteract the unscrewing force which must be applied.
In the case of the masher appliance above, the blade speed is relatively low so that an inadvertent switching on of the power unit while attempting to remove the blade is unlikely to cause injury. However, other stick mixers operate at high revolutions in which the risk of injury is high and in these mixers the blades are not removable from the drive shaft for safety reasons. This makes the blades and the insides of the skirts in which they operate difficult to clean.
It is an object of the present invention to address or at least ameliorate some of the above disadvantages.
Notes
    1. The term “comprising” (and grammatical variations thereof) is used in this specification in the inclusive sense of “having” or “including”, and not in the exclusive sense of “consisting only of”.    2. The above discussion of the prior art in the Background of the invention, is not an admission that any information discussed therein is citable prior art or part of the common general knowledge of persons skilled in the art in any country.